Tool users constantly seek to reconcile a need for tool holders having strong gripping power, with an additional need for multi-purpose holders so as to reduce tool box clutter. Some tools such as taps and screw extractors for example, require holders of differing sizes. Allen wrenches with which to adjust set screws, are sometimes available with permanent holders, sometimes without holders. Various holders are designed specifically to hold either a hack saw blade, a utility knife, a countersink, a file, a chisel, a piece of material to be soldered, and so on. Certain saber saw blades may be used only in their power machines because hand holders for them simply do not exist despite the reality that their use as hand tools is often desirable, affording the user a degree of control not possible at high speeds. The mechanic may attempt to overcome this insufficiency by gripping a saber saw blade with a pair of pliers or with a vice grip; both methods are cumbersome and unreliable.
Efforts to satisfy the need for a universal tool holder have resulted in the development of numerous devices which however, have either limited universality or weak holding power, or both.
U.S. Pat. No. 1,970,409 to O. Wiedman, shows a holder which is useful only with turning tools.
U.S. Pat. No. 3,957,096 to V. Rodman, shows a holder which is useful only with turning tools.
U.S. Pat. No. 4,566,357 to P. Carossino, shows a holder which is limited to holding only hexagonal tool bits.
U.S. Pat. No. 4,899,415 to R. Wheeler, shows a handle whose use is limited to the practice of gun cleaning.
U.S. Pat. No. 4,960,016 to R. Seals, shows a holder which is useful as a kit for storing and using (only) turning tools.
U.S. Pat. No. 5,299,475 to J. Stroop, shows a tool holder which addresses only the problem of grip size and not universality.
U.S. Pat. No. 5,819,594 to J. Sjovall, shows a hand grip for holding a turning shaft.
U.S. Pat. No. 5,480,166 to E. Milsop, shows a tool holder designed to use tool bits of various shapes and sizes in a ratchet-type turning implement. The bits are gripped between two-jaws, each tightened by an adjusting screw. This holder however, as with other such devices, has at least three limitations. First, the chuck can not grip a tool bit having lesser diameter than the size of the hole formed by the chuck's two facing V-shaped grooves. Second, the chuck will hold only tool bits conforming to the orientation of the V-grooves, that is, tool bits having straight shanks. Third, gripping strength is limited to the tightness of the two screws forcing the V-grooves against the shank. The V-groove blocks grip at one position along the shank. That is, as with all the other inventions cited above, they utilize only primary gripping. This is in contrast to the instant invention, what I refer to herein as auxiliary or "back up gripping." Further, the Milsop tool holder achieves versatility only if sockets are formed in advance on the side of its cylinder to accommodate various shapes of tools. The assortment of usable tools is thus limited to the list of sockets that have been provided. However, with back up gripping a tool holder offers versatility without prior structural preparation.
Such power tools as drills, lathes and milling machines, whether equipped with three or four jaw chucks, suffer from the same limitations as the tool holder described above. Their jaws are incapable for example, of gripping tapered shanks or shanks having otherwise nonparallel sides. This is so because the gripping edges of the jaws of a chuck remain always parallel to the longitudinal axis of the shank being gripped. A chuck is therefore capable of gripping a tapered shank at only one plane surface cross sectionally perpendicular to the longitudinal axis of the shank. This poses no difficulty with a shank whose sides are precisely parallel to the longitudinal axis, in which case the chuck grips at an infinitude of planes although the gripping occurs at only one position along the shank's length (primary gripping.) However the problem arises when the shank is irregular. In any event, sometimes gripping action is weak, in which case the tool slips within the chuck's jaws, the tool's effectiveness is diminished and its shaft is often abraded.